From 9083abbd430d902a68c25bdab019961181940a8b Mon Sep 17 00:00:00 2001
From: Navaneeth Krishnan P <33243337+navaneethkp36@users.noreply.github.com>
Date: Mon, 6 Apr 2026 17:53:18 +0530
Subject: [PATCH 1/2] fix: prepend_child sets order_value -1 causing siblings
 to reorder from -1

---
 lib/closure_tree/numeric_deterministic_ordering.rb | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/closure_tree/numeric_deterministic_ordering.rb b/lib/closure_tree/numeric_deterministic_ordering.rb
index e0e1644..172bba8 100644
--- a/lib/closure_tree/numeric_deterministic_ordering.rb
+++ b/lib/closure_tree/numeric_deterministic_ordering.rb
@@ -135,7 +135,7 @@ def append_child(child_node)
     end
 
     def prepend_child(child_node)
-      child_node.order_value = -1
+      child_node.order_value = 0
       child_node.parent = self
       if child_node.save
         child_node.reload

From 73e6b5e68fbe0d2d7c22238b77ada88a35b8df4d Mon Sep 17 00:00:00 2001
From: Navaneeth Krishnan P <33243337+navaneethkp36@users.noreply.github.com>
Date: Mon, 6 Apr 2026 19:38:29 +0530
Subject: [PATCH 2/2] fix: prepend_child causes negative order values when
 reordering within same parent

---
 lib/closure_tree/hierarchy_maintenance.rb      |  3 ++-
 .../numeric_deterministic_ordering.rb          |  2 +-
 test/closure_tree/label_order_value_test.rb    | 18 ++++++++++++++++++
 3 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/lib/closure_tree/hierarchy_maintenance.rb b/lib/closure_tree/hierarchy_maintenance.rb
index 3103dc0..951fc14 100644
--- a/lib/closure_tree/hierarchy_maintenance.rb
+++ b/lib/closure_tree/hierarchy_maintenance.rb
@@ -49,7 +49,8 @@ def _ct_after_save
           _ct_reorder_prior_siblings_if_parent_changed
           _ct_reorder_siblings
         elsif saved_changes[_ct.order_column_sym]
-          _ct_reorder_siblings(saved_changes[_ct.order_column_sym].min)
+          min = saved_changes[_ct.order_column_sym].min
+          _ct_reorder_siblings(min.negative? ? nil : min)
         end
       end
       if saved_changes[_ct.parent_column_name] && !@was_new_record
diff --git a/lib/closure_tree/numeric_deterministic_ordering.rb b/lib/closure_tree/numeric_deterministic_ordering.rb
index 172bba8..e0e1644 100644
--- a/lib/closure_tree/numeric_deterministic_ordering.rb
+++ b/lib/closure_tree/numeric_deterministic_ordering.rb
@@ -135,7 +135,7 @@ def append_child(child_node)
     end
 
     def prepend_child(child_node)
-      child_node.order_value = 0
+      child_node.order_value = -1
       child_node.parent = self
       if child_node.save
         child_node.reload
diff --git a/test/closure_tree/label_order_value_test.rb b/test/closure_tree/label_order_value_test.rb
index 968a332..2496101 100644
--- a/test/closure_tree/label_order_value_test.rb
+++ b/test/closure_tree/label_order_value_test.rb
@@ -38,6 +38,24 @@ def setup
     assert_equal 1, c.reload.order_value
   end
 
+  test 'prepend_child should produce 0-based order values when reordering within the same parent' do
+    root = Label.create(name: 'root')
+    a = root.children.create(name: 'a')
+    b = root.children.create(name: 'b')
+    c = root.children.create(name: 'c')
+
+    assert_equal 0, a.order_value
+    assert_equal 1, b.order_value
+    assert_equal 2, c.order_value
+
+    # Move c to be the first child (same parent, reorder only)
+    root.prepend_child(c)
+
+    assert_equal 0, c.reload.order_value
+    assert_equal 1, a.reload.order_value
+    assert_equal 2, b.reload.order_value
+  end
+
   test 'should set order_value on roots for LabelWithoutRootOrdering' do
     root = LabelWithoutRootOrdering.create(name: 'root')
     assert_nil root.order_value